This invention relates to a simpler and safer means of retrieving a broken marine tow cable or, in an emergency, taking a drifting barge or other vessel temporarily in tow by hooking the chain bridle or anchor chain of said vessel from a safe distance.
A problem exists when, at sea, a vessel tries to take another in tow. The case arises with a tug and tow when the barge breaks loose, usually in heavy weather, but also occurs when a vessel's powerplant fails and an assisting vessel tries to take it in tow. The need for such a device gave rise to the hook assembly described in U.S. Pat. No. 4,242,978 which can be used to retrieve the towing bridle portion of a broken tow. A hook is towed around a barge using a float to keep the hook at the proper depth until the chain bridle is snared. Said device avoids the use of an auxiliary tow line mounted on the barge or the method of putting personnel on the barge to reconnect the tow; methods which are unwieldy, unsafe, or both. U.S. Pat. No. 4,037,555 is a similar method for retrieving a buoy. The hook and float method is, however, time-consuming and not very effective in rough seas. It does not achieve or fulfill the purpose of the present invention.
My device can be used to retrieve either the towing bridle or the towing cable still attached to the drifting barge. By laterally positioning the hook assembly to either port or starboard of the towing vessel, the towing vessel can pass at a safe distance and still hook the towing bridle or cable, which is hanging down generally vertically below the drifting barge or other vessel to be towed.
There are several methods of subsurface lateral displacement, the most common being otterboards or trawl doors used for opening the mouth of a trawl net as in U.S. Pat. No. 4,879,830. Other examples are U.S. Pat. No. 4,756,268 which laterally displaces towed seismic cables, and U.S. Pat. No. 3,507,068 and other, small devices used to control fishing lines or trolling lines. However, the method of using lateral displacement to retrieve a hanging cable is new.
The preferred method of restoring a broken tow is to retrieve the tow cable and "strip" the cable, bringing it aboard the towing vessel a section at a time until the broken end is reached, then coupling it to the residual tow cable still on the towing winch. However, if the cable broke at the connection to the chain bridle, if the weather is severe, or if the drifting barge is in danger of going aground, my device can be used to hook the chain bridle, get the barge under control, and tow until such time as the weather abates or to a more sheltered or otherwise suitable location where a more permanent coupling can be made.
In the event of a vessel in distress, the normal procedure is to send over a small "shot line" or "heaving line" which is connected to larger and larger lines until a tow line of suitable diameter is reached and made fast to the distressed vessel. This method can involve a great deal of effort and in severe weather is highly dangerous. Using my system, the distressed vessel need only let out a suitable length (e.g. two "shots", or 180 feet) of anchor chain and an emergency tow can be easily and safely established.
The subjected device can be easily carried aboard the towing or rescue vessel and can be shackled to a tow line in time of need. The depth and lateral position of the hooking assembly is controllable by the length of the recovery tow line deployed and the speed of the vessel (general guidelines for tow cable lengths and towing speeds may be engraved on the device).
The speed and simplicity of my device combined with its optional bidirectional capability makes it advantageous even in relatively shallow water. By preventing a barge or vessel from going aground lives and property can be saved and, in the event of a petroleum or bulk chemical barge, massive ecological damage can be averted.